The objective of this program is to measure the lateral mobility of various components of the cell surface in "normal" mouse fibroblasts in culture as compared to their virus transformed counterparts. This will be done by studying emission recovery after photobleaching from fluorescent probes specific for the cell surface. The probes to be used include antibodies to cell surface antigens and plant lectins specific for the cell surface (work in progress) as well as lipid "fluidity" probes. A fluorescence microscope capable of detecting emission from restricted areas, as small as 1 micron in diameter, of the cell periphery will be employed. Studies will begin with measurements on single normal and transformed cells as a function of phase in the cell cycle and be extended to cells in contact situations. Such measurements should extend our grasp of the principle governing the motions of cell surface macromolecules. Insight into the role of a dynamic cell surface in cell-cell recognition phenomena should also gained. In particular, it is hoped the proposed measurements to characterize aspects of cell surface dynamics will shed light on the altered social behavior of neoplastically transformed cells in culture. BIBLIOGRAPHIC REFERENCES: K. Jacobson, C. Wenner, G. Kemp, and D. Papahadjopoulos, "Surface Properties of Phorbol Esters and Their Interaction with Lipid Monolayers and Bilayers", Cancer Research, 35: 2991 (1975). K. Jacobson, E-S. Wu, and G. Poste. "Measurement of the Translational Mobility of Concanavalin A in Glycerol-Saline Solutions and on the Cell Surface by Fluorescence Recovery After Photobleaching", Biochim. Biophys. Acta, 433: 215 (1976).